UNION (Ultrasonic Nuclear InspectiON)

The goal is to achieve nondestructive inspection (NDI) of nuclear power generation and reprocessing plant pipework carrying cooling water or generator steam, along pipe runs that are embedded in concrete, buried underground and/or clad in protective coatings such as plastic or bitumen. Key examples are (i) primary coolant and steamline pipework passing respectively through the concrete primary and secondary containment walls; and (ii) pipework for spent fuel cooling. Any breach of these pipes carries risks of nuclear radiation leakage and shut down for repair. Embedding/cladding materials all highly attenuate ultrasound, making current ultrasonic NDI practice in nuclear plant unusable or requiring cladding removal. The innovative solution is to use low frequency guided ultrasonics (LFGU), which can propagate through embedding and cladding materials, in both periodic inspection and continuous structural health monitoring modes. Enhanced signal to noise ratios through new high power transducers and low noise receiver combined with advanced signal processing for trend analysis will allow detection of smaller crack and corrosion defects than hitherto possible by LFGU.